For an image sensor SOC that integrates a sensor array with an image processing component, chip defects are typically difficult to uncover until a certain sensed image is displayed with obvious visual errors. Discovery of any chip defect detected only at display time is obviously highly undesirable. What is needed is to test for any defects before the image sensor SOC is utilized in any application.
However, using conventional testing techniques, testing the output of the above image sensor SOC poses several problems. First, when the test result indicates image errors, which component (the sensor array or the image processing component) caused the indicated image error is difficult to discern. Second, situations can arise where image errors caused by the sensor array defects are “masked” by the image processing component. That is, the image errors caused by the sensor array can go undetected until display time.